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Liao K.-W.,National Taiwan University of Science and Technology | Cheng M.-Y.,National Taiwan University of Science and Technology | Chiu Y.-F.,Harbor and Marine Technology Center | Lee J.-H.,National Taiwan University of Science and Technology
Construction and Building Materials | Year: 2016

Frequency is often considered to be an ideal safety indicator in bridge health monitoring. Many scholars have related bridge scour depth to frequency. However, few of previous studies have focused on finding a threshold frequency that corresponds to the limit state of bridge failure. Thus, this study focuses on finding a critical frequency ratio (Rc) that can be used to distinguish between undamaged and damaged bridges. The bridge limit state was calculated by subtracting the demand from the capacity of a bridge. Both the capacity and demand envelopes of a bridge were determined using pushover analyses. Nonlinear behaviors of core/cover concrete and steel reinforcement were considered. In the end of this study, a range of frequency ratio is proposed to be an on-site indicator to evaluate bridge safety. Although the proposed safety frequency ratio is consistent with a field observation, the parameters used in this study are from Taiwan only. In addition, the proposed safety ratio only considered bridges with a single pier against flood hazard. The limits should also be considered for further applications. © 2015 Published by Elsevier Ltd. Source


Cheng M.-Y.,National Taiwan University of Science and Technology | Chiu Y.-F.,Harbor and Marine Technology Center | Wu Y.-W.,National Taiwan University of Science and Technology | Ou Y.-C.,National Taiwan University of Science and Technology | And 3 more authors.
Journal of the Chinese Institute of Civil and Hydraulic Engineering | Year: 2013

Bridges are a vital and significant component of Taiwan's transportation infrastructure. Therefore, regular and comprehensive inspections of existing bridges are necessary to prevent damage and traffic disruption and reduce earthquake-related damage and casualties. However, due to the large number of bridges in Taiwan, the time and budget required to perform traditional structural analyses (preliminary assessment, detailed analysis) on every bridge to calculate yield acceleration (Ay) and collapse acceleration (Ac) values make doing so impractical. This paper integrates material degradation, pushover analysis, and artificial intelligence to create a new inference model as an alternative to traditional structural analysis. Historical cases are used to infer Ay and Ac values by mapping relationships between the preliminary assessment factors (input) of historical cases and detailed assessments of Ay and Ac values (output). Using the proposed inference model to predict Ay and Ac values, bridge maintenance planners can quickly and more cost effectively assess bridge earthquake damage probabilities as a guide to identifying priority bridge maintenance projects. Source


Lee M.-G.,Chaoyang University of Technology | Huang Y.-S.,Chaoyang University of Technology | Chang T.-K.,Harbor and Marine Technology Center | Pao C.-H.,Chaoyang University of Technology
Geotechnical Special Publication | Year: 2011

Pervious concrete pavement is air and water permeable, the soil underneath can be kept wet and rainwater can quickly filter into ground, allowing groundwater resources to renew in time. Pervious concrete also possesses many other advantages including sound absorption and skid resistance and is therefore suitable for use in Taiwan's rainy and humid environment. However, the prevalence of air voids result in low strength, so pervious concrete has not been suitable for use in surfacing roads with heavy traffic loadings. In this study we sought to determine the suitable mix of cement, silica fume, superplasticizer, steel fiber, course aggregate and so on for a pervious concrete pavement strong enough for road surfacing. The results showed that the compression strength of one pervious concrete core specimen from the simulated field site was up to 275.7kgf/cm2 and exceeded the ordinary concrete structure specification. The flexural strength of one pervious concrete sawed specimen from the simulated field site was up to 48.11kgf/cm2 and exceeds the highway rigid pavement specification (45 kgf/cm2). Four mixtures were trialed with void contents ranged from 18.8 to 31.9% and densities from 1,890 to 2,034 kg/m3. The field permeability testing method developed for asphalt pavements has been found to work well for pervious concrete. Water penetration was very good with field permeability test showing about 1,100ml/15sec. This study of the simulated field pervious concrete pavement will be valuable for highway design and construction. © 2011 ASCE. Source


Cheng M.-Y.,National Taiwan University of Science and Technology | Chiu C.-K.,National Taiwan University of Science and Technology | Chiu Y.-F.,Harbor and Marine Technology Center | Wu Y.-W.,National Taiwan University of Science and Technology | And 3 more authors.
Journal of the Chinese Institute of Civil and Hydraulic Engineering | Year: 2014

Proper maintenance and restoration strategy for bridges is an essential issue, for Taiwan is an island with frequent earthquake, typhoon and heavy rain, thus, bridge competent might deteriorate more seriously. Nowadays, the bridge inspections in Taiwan are almost visible (tangible), while the invisible (potential) risks such as earthquake and scour resistant capacity are not taken into account. This paper considers main risk factors as the competent deterioration, scour and earthquake. In order to ensure the safety and extend the life-span for bridges and the government limit budget, this study proposes the novel model, the Bridge life cycle Maintenance Strategy Optimization Model. In the model, first, the study uses Monte Carlo simulation to estimate the bridge maintenance probability from the historical data. Second, using the artificial intelligence (AI) ES1M model to estimate risk impact influence cost from the relationship through the input data (DER & U) and output data (historical maintenance cost). Third, sum up each risk factor's multiplication of bridge maintenance probability and risk influence cost to obtain the risk cost as E (Cost). Last, the model utilizes (SOS, Symbiotic Organism Search) algorithm to obtain the minimum LCC cost. As a result, this study can provide the optimal maintenance timing and cost as maintenance strategy for bridge management division. ©, 2014, Chinese Institute of Civil and Hydraulic Engineering. All right reserved. Source


Liau J.-M.,Taiwan Ocean Research Institute | Hsu T.-W.,National Cheng Kung University | Hsu T.-W.,National Taiwan Ocean University | Wang L.-W.,Taiwan Ocean Research Institute | And 2 more authors.
Proceedings of the International Offshore and Polar Engineering Conference | Year: 2013

In this study, a parallel computing and high-resolution threedimensional tidal model, the Princeton Ocean Model (POM), was employed to simulate ocean circulation and the tidal current simultaneously in the coastal waters of Nanwan Bay at Taiwan. The distribution of current and temperature in the Nanwan Bay and baroclinic tidal energy flux in the Luzon Strait are simulated. The barotropic-to-baroclinic tidal energy conversion rate and barotropic tidal energy fluxes were further analyzed and was used to locate the generation site of internal tides in the Luzon Strait. From simulation results, we further study the cold water of upwelling at Nanwan Bay. Copyright © 2013 by the International Society of Offshore and Polar Engineers (ISOPE). Source

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